The relationships between urinary albumin excretion and serum levels of lipids, apolipoproteins and aortic pulse wave velocity (PWV) were investigated in 117 NIDDM with normoalbuminuria (overnight urinary albumin excretion index;UAI<15mg/g·Cr), 5 6 NIDDM with microalbuminuria (UAI between 15 and 199mg/g·Cr) and 21 NIDDM with macroalbuminuria (UAI≥200mg/g·Cr). Serum total cholesterol, triglyceride, apo B, apo E and the apo B/apo A-I ratio became significantly higher and HDL-cholesterol tended to decrease as UAI increased. Particularly, in the patients with microalbuminuria, triglyceride, apo B and the apo B/apo A-I ratio were significantly higher than those in the normoalbuminuric patients (p<0.05). In addition, PWV was significantly faster in microalbuminuric and macroalbuminuric patients than in normalbuminuric subjects (p<0.02, p<0.05), depending on the severity of albuminuria. Thus, PWV correlated significantly with the apo B/apo A-I ratio (p<0.001). These results indicate that diabetic nephropathy, even in its early phase, could induce significant pathological alterations in lipid and apoprotein levels, furthering PWV as an index of atherosclerosis.